Cousin of Tzar Alexander III, second cousin of Tsar Nicholas II, and a career soldier, whose military experience stretched from the Russo-Turkish War of 1877-78 to the First World War. On 3 August 1914 he was made Commander in Chief of the Russian army, where he came under pressure from the French to launch attacks before Russian mobilization could be completed, leading to the disasters of Tannenburg and Masurian Lakes. He was one of the few competent members of the Russian High Command, although the individual army commanders had more influence at the front. By September 1914 he had reorganised his armies in preparation for an attack on Silesia, the heart of German mineral production.
However, the Germans launched a counterattack, which resulted in the battle of Lodz (12-25 November 1914), where Nicholas showed his skill, managing to turn a potential disaster into a tactical victory with his own counterattack. 1915 saw disaster strike the Russian army, which from June-September was forced to retreat up to three hundred miles back into Russia, abandoning Russian occupied Poland. Grand Duke Nicholas managed the withdrawal with great skill, and managed to preserve his armies intact, and stop the withdrawal turning into a rout that would have meant defeat for Russia. However, in a typically inept move, Tsar Nicholas II decided to take personal command of the war against Germany and Austria, and on 21 August the Grand Duke was removed from command, and made Vice-Roy of Caucasia, in command of the war against the Turks.
He arrived on 24 September 1915, and found himself working with General Yudenich, one of the few skilled Russian generals of the war, who he retained as his field commander. On the Caucasus front the Grand Duke was able to play a bigger part in the planning of the war, and with Yudenich put together a plan for an offensive in 1916, which resulted in one of the few clear-cut Russian successes of the war, pushing the Turks back over one hundred miles, and then held on to the newly gained territory until the Russian collapse of 1917. He was removed from command after the February Revolution of 1917, and went into exile in 1919, first in Italy, and then finally in France.